• 대한금속재료학회지
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• 제50권5호
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• pp.369-374
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• 2012

Nanopowders of Mo, Ta and Si were made by high-energy ball milling. A dense nanostructured $MoSi_2-TaSi_2$ composite was sintered by the high-frequency induction heated combustion method within 2 minutes from mechanically activated powder of Mo, Ta and Si. A highly dense $MoSi_2-TaSi_2$ composite was produced under simultaneous application of a 80 MPa pressure and the induced current. Mechanical properties and microstucture were investigated. The hardness and fracture toughness of the $MoSi_2-TaSi_2$ composite were $1200kg/mm^2$ and $3.5MPa.m^{1/2}$, respectively. The mechanical properties were higher than those of monolithic $MoSi_2$.

• 한국자기학회지
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• 제9권4호
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• pp.203-209
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• 1999

CoCrTa/Cr 자성박막의 Cr 하지층에 Mo와 Si을 첨가하여 제조한 박막의 자기적 성질에 미치는 Mo와 Si의 영향에 대하여 조사하였다. 증착시 사용된 장비는 DC magnetron sputtering system이었고, CoCrTa 자성층의 두께는 30.0$\AA$으로 Cr 하지층의 두께는 700$\AA$으로 고정하였으며 기판의 가열온도는 26$0^{\circ}C$이었다. CrMo 하지층의 박막이 순수한 Cr 하지층에 비하여 약 200 Oe의 보자력 증가를 나타내었다. 하지만 Si을 첨가하였을 경우엔 첨가량의 증가에 따라 보자력이 점차 감소하는 것으로 나타났다. CrMo 하지층에서는Mo를 첨가함에 따라 Cr 하지츠의 (200)면의 결정배향성이 증가하였고, Mo를 첨가한 Cr(200)과 CoCrTa(110)의lattice misfit가 Si을 첨가한 경우보다 작았고, 이것이 보자력 증가의 원인이었다.

• 한국세라믹학회지
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• 제48권6호
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• pp.559-564
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• 2011

In order to investigate the behavior of $SiO_2$ in the molybdenum silicide powders, crystal structure of these powders was measured by XRD, in addition, surface composition and surface phase (or chemical states) and microstructure were analysed by XPS and TEM, respectively. Mo-silicide powders containing $SiO_2$ were synthesized by SHS (Self-Propagating High-Temperature Synthesis) technique. In XRD result, according to increase of $SiO_2$ contents, the crystal structure for synthesized $MoSi_2$ powders was still typical $MoSi_2$ bct without any other phases. By XPS analysis, the surface of Mo and Si source powders was covered with $MoO_3$ and $SiO_2$, respectively, and the surface of synthesized $MoSi_2$ powder was also covered with $MoO_3$ and $SiO_2$, which were stable oxides at room temperature. However, according to increase of $SiO_2$ addition, $MoSi_2$ phase in XPS spectra decreased and $SiO_2$ phase increased relatively in synthesized $MoSi_2$ powders. From the results by XPS and XRD, we found that the existent $SiO_2$ has amorphous structure. In the microstructure, the small particulates of the synthesized products added $SiO_2$ agglomerated together to form larger clusters (from ~10 nm to ~1 ${\mu}m$). From TEM, XPS, and XRD results, we found that the out layer of agglomeration of synthesized $MoSi_2$ powder is surrounded by amorphous $SiO_2$.

• 한국재료학회지
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• 제6권1호
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• pp.57-66
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• 1996

MoSi2 heating elements were fabricated by sintering of MoSi2 powders which were synthesized through SHS(Self-propagating high-temperature synthesis). Their high-temperature oxidation behavior in air through SHS(Self-propagating high-temperature synthesis). Their high-temperature oxidation behavior on air at 1000-1600$^{\circ}C$ was investigated through a high-temperature X-ray diffractomer and isothermal heating in a muffle furnace. The thermal expansion of MoSi2 and SiO2 was studied by measuring their lattice parameters on heating. The linear expansion coeffcient of MoSi2 along c-axis was about 1.5 times larger than that along a-axis showing a strong thermal anisotropy. Few $\mu\textrm{m}$-thick Mo5Si3 layer was found beneath SiO2 layer suggesting that The major reaction products would be SiO2 and Mo5Si3. The Si-rich bentonite resulted in the faster growth of MoSi2 grains probably by enhancing the mass transport when they are melted during high-temperature oxidation.

• 마이크로전자및패키징학회지
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• 제8권2호
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• pp.19-24
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• 2001

EUV 노광공정의 반사형 노광계 및 마스크에 사용되는 Mo/Si 다층박막 착탁 시 발생하는 각 층의 두께 변화와 상호확산 층 (inter-diffusion layer)이 생성될 경우에 대하여 이들이 다층박막 반사도에 미치는 영향을 전산모사를 통하여 알아보았다. 본 연구그룹에서 개발한 다층박막 반사 시뮬레이션 프로그램을 사용하여 Mo/Si 40-period박막의 반사토플 계산한 결과, 각각의 period가 두께의 편챠(28%)를 갖는 경우, 모든 period가 같은 두께를 갖는 다층박막에 비해 최대반사도가 10.8% 감소가 되었으며 두 층간 물질 사이의 상호확산(interdiffustion) 층을 가정하였을 경우, 다층박막의 경우 그렇지 않은 경우에 비해 4.7%의 최대반사도가 감소가 예상되었다. 그리고 각 층의 적층에 따른 반사도의 변화를 시뮬레이션 프로그램을 통해 계산한 결과 반사도는 25층까지 계속 증가하며 26층부터 불규칙한 경향성을 가지며 증가와 감소를 반복함을 알 수 있었다.

• 한국분말재료학회지
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• 제4권4호
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• pp.298-303
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• 1997

The activated sintering behavior of $MoSi_2$ powder compacts with addition of 0.5 and 1.0 wt.%Ni during the sintering under As atmosphere was studied. The shrinkage was measured and the microstructures were observed by SEM (scanning electron microscopy) and BEI (backscattered electron image) along with the phase analysis by EDS during heating up to 155$0^{\circ}C$ and holding for various time at 155$0^{\circ}C$. The most of shrinkage occurred upon heating and 92% of theoretical density was attained after sintering for 1 hr at 155$0^{\circ}C$. However, little shrinkage ensued even for prolonged sintering over 1 hr at 155$0^{\circ}C$. A liquid film formed at about 135$0^{\circ}C$ along necks and grain boundaries. The polyhedral grain structure composed of $(Mo,Ni)_5Si_3$and $Ni_2Si$ across the $MoSi_2$ grain boundary developed at 155$0^{\circ}C$. It was concluded that the activated sintering of $MoSi_2$ powder by Ni led to the diffusion of Si into Ni decreasing the liquidus temperature and the enhanced diffusion of Mo and Si through such a liquid phase and/or interboundary of $(Mo,Ni)_5Si_3$.

• 한국세라믹학회지
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• 제31권4호
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• pp.399-406
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• 1994

The SiC/MoSi2 composite material was prepared by infiltration with the mixture of metal Si and MoSi2 into the preform of $\alpha$-SiC and graphite under the vacuum atmosphere of 10-1 torr. The mechanical properties, phases and microstructural characteristics have been investigated by employing an universal testing machine, scanning electron microscope and X-ray diffractometer. With the increase of MoSi2/Si mixing content, the quantity of the residual silicon phase was decreased and the hardness and fracture toughness of composite materials were increased. Also, as the infiltration temperature increased, a lot of fine-grained $\beta$-SiC phases, which were produced from the reaction of graphite and liquid silicon melt, were transformed to $\alpha$-SiC phases.

• 공업화학
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• 제10권2호
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• pp.231-236
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• 1999

결정상과 분산도가 조절된 $MoO_3$/$SiO_2$ 담지촉매를 제조하여 촉매의 표면특성과 디벤조티오펜 탈황반응의 활성도를 고찰하였다. Mo의 표면담지량은 4 atoms $Mo/nm^2$이었으며, 실리카 표면 위에 형성된 $MoO_3$의 결정상은 sintered hexagonal, sintered orthorhombic, 및 dispersed hexagonal상이었다. XRD, Raman, 및 $O_2$ 흡착 결과 $MoO_3$의 표면분산도는 sintered hexagonal < sintered orthorhombic < dispersed hexagonal 순으로 증가하였다. TPR 결과 $MoO_3$ 결정은 $650^{\circ}C$에서 $MoO_2$로, $1000^{\circ}C$에서 Mo로 환원됨을 알 수 있었다. 디벤조티오펜 탈황반응을 30기압, $350{\sim}500^{\circ}C$ 온도범위에서 수행하였으며, 실험 결과 활성도는 $MoO_3$ 결정체의 $SiO_2$ 표면에서의 분산도에 비례하여 증가함을 알 수 있었다.

• 한국결정성장학회지
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• 제30권5호
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• pp.200-207
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• 2020

SHS 법으로 MoSi₂ 분말, (Mo_1/2W_1/2)Si₂ 분말 및 WSi₂ 분말을 합성하고 이 분말들을 500℃, 1,000℃, 1,200℃, 1,300℃, 1,400℃, 1,500℃ 및 1,600℃에서 열처리한 다음, 결정구조 및 열중량 변화 등을 관찰하였다. Mo-W-Si계의 silicide 분말은 500℃의 저온에서도 산화 반응이 일어나며, 저온 산화 및 분해로 생성되는 결정상은 MoO₃이었다. 1,200℃ 이상에서 열처리를 한 경우에 분해반응으로 생성된 SiO₂의 결정상은 상온에서 흔히 관찰되는 α-quartz가 아닌 α-cristobalite 상으로 생성되었다. W이 포함되면 저온과 고온에서 분해 반응이 더 많이 일어나는 것으로 나타났으며, 분말을 성형하여 소결한 시편의 경우에 MoSi₂와 (Mo_1/2W_1/2)Si₂는 저온이나 고온에서 1시간 열처리를 하더라도 저온산화에 의한 분해와 그에 따른 질량 변화 반응을 관찰하기 어려웠지만 WSi₂는 저온 산화에 의하여 소결 자체가 어려웠다.

• 한국해양공학회지
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• 제25권4호
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• pp.66-71
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• 2011

The flexural strength of $MoSi_2$ based composites reinforced with Nb sheets has been investigated, based on the detailed examination of their microstructure and fractured surface. Both sintered density and porosity of Nb/$MoSi_2$ composites were also examined. Nb/$MoSi_2$ composites were fabricated by different conditions such as temperature, applied pressure and its holding time, using a hot-press device. The volume fraction of Nb sheet in this composite system was fixed as 10%. The characterization of Nb/$MoSi_2$ composites were investigated by means of optical microscopy, scanning electron microscope and three point bending test. Nb/$MoSi_2$ composites represented a dense morphology at the interfacial region, accompanying the creation of two types of reaction layer by the chemical reaction of Nb and $MoSi_2$. Nb/$MoSi_2$ composites possessed an excellent density at the fabricating temperature of $1350^{\circ}C$, corresponded to about 95% of theoretical density. The flexural strength of Nb/$MoSi_2$ romposites were greatly affected by the pressure holding time at the same fabricating temperature, owing to the large suppression of porosity in the microstructure. Especially, Nb/$MoSi_2$ composites represented a good flexural strength of about 310 MPa at the fabricating condition of $1350^{\circ}C$, 30MPa and 60min, accompanying the pseudo-ductile fracture behavior by the deformation of Nb sheet and the interfacial delamination.